Green screen testing


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"Green Screen is a procedure wherein two images can be mixed, the image in front is removed in order to reveal the image that is behind it. Since image sensors in digital cameras are sensitive to the color green, this is why the color is used more often in the background if compared with any other hue. Hence, this channel contains minutest noise and creates clean and clear mask. This technique is used from weather forecasting to making of blockbuster feature films.

Chroma key compositing (or chroma keying) is a technique for compositing (layering) two images together. A color range in the top layer is made transparent, revealing another image behind. The chroma keying technique is commonly used in video production and post-production. This technique is also referred to as color keying, greenscreen, and bluescreen. It is commonly used for weather forecast broadcasts, wherein the news presenter appears to be standing in front of a large map during live television newscasts, but in a television studio it is actually a large blue or green background. The meteorologist stands in front of a bluescreen, and then different weather maps are added on those parts in the image where the color is blue. If the meteorologist wears blue clothes, his clothes will become replaced with the background video. This also works for greenscreens, since blue and green are considered the colors least like skin tone.[3] This technique is also used in the entertainment industry, for example for special effects." (250 words)

http://en.wikipedia.org/wiki/Chroma_key

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GREEN SCREEN / CHROMA KEY TESTING - RESEARCH PROJECT
Test a number of green screen options
Intro (200 words)
  • Describe the green screen technique / effect?
  • What is it also called?
  • What is green screen used for ? – List Uses
  • What colours can be used?
  • Why is it important to wear certain colours?
  • List famous films that use green screen?

Techniques (200 words)
  • What equipment do you need to make green screen?
  • How do you make green screen happen using – moving film and IMovie
  • How do you make green screen happen using – photoshop and IMovie
  • List tips that you have learnt that will help to make green screen?

Testing
  • Take film footage with a green screen / blue screen background
  • Create images using Photoshop with a green or blue background
  • Create or download backgrounds to put behind the green screen
  • Import the film / stills into IMovie
  • Layer them using the green / blue screen option
  • Take screen shots (shift, command, 4)

Results (200 words)
  • Place your screen shots / images in Pages
  • Label each test

Comparative Reflection
  • What green screen effects were the most effective why (150 words)
  • How could you use green screen effects in your product? (50 words)

ASSESSMENT CRITERIA – Investigating, Planning, Evaluating
I4 Investigation of product material options and analysis for product use.
Pl3 Testing, modification, and validation of ideas or procedures.
E2 Evaluation of the effectiveness of the product or system realisation process.

References
RESOURCES:
http://en.wikipedia.org/wiki/Chroma_key
http://support.apple.com/kb/PH2245?viewlocale=en_US
http://www.mediacollege.com/video/special-effects/green-screen/
http://zephyrphotoworks.com/greenscreenDetail/136


Using a Green Screen from Vimeo Video School on Vimeo.